Pyramids

What is the ratio between the volume of a triangular pyramid and the volume of a square pyramid, all of whose edges have the same length?

Notes:

• A "triangular pyramid" is a pyramid whose basis is a triangle; a "square pyramid" is a pyramid whose base is a square.
• All the edges in both pyramids are equal in length.
• I heard this from Shahar Mozes, who heard it from someone selling wooden puzzles in the "midrahov" (Ben-Yehuda Street) in Jerusalem.